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摘 要 球磨机高性能磨球广泛应用于冶金矿山、建材、化工、火力发电等行业球磨机。磨球是球磨机中的粉碎介质，用于粉碎磨机中的物料。轧制钢球就目前生产效率最高，性能优良的钢球制备方法。 通常的轧制钢球，轧制成型后直接进行水淬，并低温回火，得到 HRC60 以上的高耐磨性的抗磨钢球，这类钢球在湿磨情况下表现出优良的耐磨性能。但因为低合金钢淬火获得的马氏体稳定性差，随着温度提高，硬度下降比较明显，使得轧制并水淬的钢球不适应干磨的工况条件。本文就是进行系统的等温淬火工艺研究，试图通过等温淬火获得下贝氏体组织，下贝氏体在具有比马氏体更优良的组织稳定性，其硬度随回火温度变化较小。 本文选取生产中用于轧制小型钢球的 B2 钢作为原材料，选择低熔点复合盐，用熔融盐作为等温淬火介质，系统研究了 B2钢在不同温度下等温淬火后组织与性能；对等温淬火获得的下贝氏体组织，进行系列回火研究其回火稳定性，分析其干磨条件下的使用可行性。研究结果表明，在 280℃盐浴等温淬火时，得到针状下贝氏体组织，且数量较多，分布均匀，硬度达到耐磨钢球对性能指标的要求，回火处理后，材料的微观组织变化不大，仍以下贝氏体为主，回火后的硬度虽有所下降，但仍能满足耐磨钢球对性能指标的要求。直接水淬试样在260~320℃范围内回火后，材料的微观组织由马氏体转变成回火马氏体，发生了明显的变化，硬度也大幅度下降。58613
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毕业论文关键字：高性能磨球；等温淬火；下贝氏体；工艺；温度；
Abstract High performance grinding ball mill is widely used in metallurgy, mining, building materials, chemical industry, thermal power and other industries ball mill. The grinding ball is the grinding medium in the ball mill, which is used to crush the material in the mill. Rolling steel ball has the highest production efficiency and good performance. The usual rolling steel ball, directly after the rolling process of water quenching, and low temperature tempering, get more than HRC60 high wear resistant steel ball, this kind of steel ball in the wet grinding condition showed excellent wear resistance. But because of the poor stability of martensite obtained by the quenching of the low alloy steel, with the increase of temperature, the hardness decreased obviously, which makes the rolling and water quenched steel balls do not adapt to the dry condition. This paper is research of austempering process of system and trying to obtain lower bainite isothermal quenching, lower bainite has more excellent than martensite microstructure stability, its hardness with the tempering temperature changes a little. This paper selects production for small ball rolled B2 steel as raw materials, low melting point compound salt, molten salt as the isothermal quenching medium and study of the system of lower bainite B2 steel at different temperature after isothermal quenching microstructure and properties; of isothermal quenching of body tissue, series tempering tempering stability research and analysis of the dry grinding application feasibility conditions. The results show that the acicular bainite tissue obtained at 280 ℃ austempering and number, uniform distribution, to reach the hardness wear resistant steel ball on the performance index requirements, after tempering, microstructure changes little, still lower bainite mainly, back to the fire after the hardness despite the decline, but still can meet the requirements of wear resistant steel ball on the performance index. After tempering in the range of 260~320 ℃, the microstructure of the samples changed from martensite to tempered martensite, and the hardness was greatly decreased.
Keywords: High performance grinding ball; isothermal quenching; lower bainite; process; temperature;